monsoons

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The annual summer monsoon that drops rain onto East Asia, an area with about a billion people, has shifted dramatically in the distant past, at times moving northward by as much as 400 kilometers and doubling rainfall in that northern reach. The monsoon’s changes over the past 10,000 years likely altered the course of early human cultures in China, say the authors of a new study.

As the second most recent ice age was ending and its glaciers began to retreat, the Earth experienced a large, abrupt climate change that shifted the thermal equator southward by about 4 degrees, according to a new study that for the first time tracks that shift in millennial detail, showing how the Northern Hemisphere cooled and the Southern Hemisphere warmed over the span of a few hundred years. The change would have affected the monsoons, today relied on to feed more than half the world’s population, and could have helped tip the climate system over the threshold for deglaciation, said lead author Allison Jacobel.

Scientists at Columbia University’s Lamont-Doherty Earth Observatory have found that currents connecting the Indian and Pacific Oceans are colder and deeper than originally believed. This discovery may one day help climate modelers predict the intensity of the Asian monsoon or El Niño with greater accuracy and with more lead-time than is currently possible.